Create Transaction on MariaDB to set expiry time for ip blacklist - sql

Question

The question I used to help build this transaction is here:
How to add 1 hour to currrent_timestamp in mysql which is the default value?
I'm trying to create a transaction in my database to fill in the allowed column in my mariadb database table blacklisted_ips. I want the allowed column to be an hour after my added column which has a default value of CURRENT_TIMESTAMP. Here is my transaction so far:
CREATE TRIGGER before_insert_on_blacklisted_ips BEFORE INSERT ON blacklisted_ips FOR EACH ROW BEGIN
SET NEW.allowed=NOW()+INTERVAL 1 HOUR;
END;
The error message I'm getting is the following:
#1064 - You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near '' at line 2
Here is my table schema:
CREATE TABLE blacklisted_ips (
ip_id int(11) NOT NULL AUTO_INCREMENT,
ip_add varchar(15) NOT NULL,
added timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP,
allowed timestamp NOT NULL,
PRIMARY KEY (ip_id)
);

Answer 1

In MySQL, there's an ambiguity between the ; that terminates a CREATE TRIGGER statement, and the possible ; characters that terminate individual statements in the body of the trigger.
The error you got is confusing:
#1064 - You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near '' at line 2
Normally a syntax error includes the text of the statement following the position where the syntax parser got confused. But in your case, it got confused at ;, thinking it was the end of the CREATE TRIGGER statement. Therefore the error occurs at the termination; there is no text following the error as far as the parser is concerned.
The same issue affects CREATE PROCEDURE and CREATE FUNCTION.
To fix the ambiguity, MySQL client supports a builtin command to change the DELIMITER, so you can change it to something distinct from any sequence of characters that appear in the body of your routine.
DELIMITER ;;
CREATE TRIGGER before_insert_on_blacklisted_ips BEFORE INSERT ON blacklisted_ips
FOR EACH ROW BEGIN
SET NEW.allowed=NOW()+INTERVAL 1 HOUR;
END ;;
Alternatively, since in your case the trigger is a single-statement trigger, you don't need a BEGIN...END block at all. This way you can skip changing the DELIMITER, because the ; that terminates your CREATE TRIGGER is the same ; that terminates the single statement of the trigger.
CREATE TRIGGER before_insert_on_blacklisted_ips BEFORE INSERT ON blacklisted_ips
FOR EACH ROW
SET NEW.allowed=NOW()+INTERVAL 1 HOUR;
P.S.: This is documented with an example here: https://dev.mysql.com/doc/refman/8.0/en/trigger-syntax.html